When working with more than one trunk or branch get a line level and stretch a line at the elevation you want the treehouse at. Check out, side of tree that beam will be attached to see if the tree is healthy at that elevation. This is something you will need to do so your platform has a good chance of coming out level. If the branches that you are going to attach too, lean out like on this tree, it is best to attach too the side or inside of the branch and not the outside. Sometimes it may be helpful to layout your beams and joist on the ground first to see exactly what elevations you put your brackets at.eldom do a group of trees or branches grow in rectangular shape. These four trees are not perfectly plum. To get true measurements you most measure at the elevation you are going to put the platform at.

First get the circumference and elevation

Two Trees

Three Trees

FourTrees

Then get inner most points

Now get your distances between each point

Here A and C where Khosrow wants to attach at 10' the branches lean out. If the sides of B and D where the beam is to be attached is straight up and down that's good. If they lean out to much like A and C then you either have to hange your beam from the Garnier Limb® or attach to the inside of D and B.

I think of the underside of a platform as an exposed ceiling, when looking at it from the ground. Therefore I build them as such, using logs and 4by's instead of 2by's. I also stack the joists on top of the beams. This allows for greater strength and versatility. Here I have cantilevered the joists out the front of where I'm going to put the treehouse so I can put a porch there. I could put a porch all the way around the treehouse by cantilevered the main beams out past the trees. this treehouse is big enough and I would be taxing the Garnier Limb's® safety range. Note: when using the GLs with the long arm extensions. Make sure that you put them in very close to level.

You can also do it on paper. Measure all sides and diagonals AB,AC,AD,CB,CD and DB, then plot them on graft paper using a compass. If all the lines connect you did a good job of measuring. Here the beams will be put in on different sides of the trees so that we can square up the front and back of the treehouse.